Fluid motor



-J. M. MCDONNELL ETAL 7 2,802,458

Aug. 13, 1957 FLUID MOTOR 2 Sheets-Sheet 1 Filed Oct. 22, 1953 INVENTORS u M Z w .4 M M n M w p .n U.

by A mmfi w a J M Aug. 13, 1957 J. M. MODONNELL ETAL 2,802,458

FLUID MOTOR Filed Oct. 22, 1953 I v 2 Sheets-Sheet 2 u. V i I 5! INV ENTORS Joseph M. McDonnell Henry D. Mowers.

a 1/. Wmzzu The/r Af/arney 2,802,458 Patented Aug. 13, 1957 FLUID MOTOR Joseph M. McDonnell, Rochester, and Henry D. Mowers,

Spencerport, N. Y., assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application October 22, 1953, Serial No. 387,730

11 Claims or. 121-797 This invention pertains to fluid pressure operated mo tors, and particularly to fluid motors adapted for actuating oscillatable windshield wipers.

The use of fluid motors for actuating oscillatable windshield wipers has become widespread in recent years. However, the majority of such motors are of the suction operated type, rather than of the pressure type. This invention relates to a motor of the latter type, and may be operated by any suitable fluid medium under pressure, be it a liquid or a gas. Accordingly, among our objects are the provision of a fluid motor having valve means controlled by movement of the piston thereof, the further provision of a fluid motor constructed and arranged so as to move wiper blades throughout a normal wiping range and to a parked position; and the still further provision of means for controlling the speed of motor operation.

The aforementioned and other objects are accomplished in the present invention by providing a fluid motor assembly with a mechanically actuated pilot valve and a servo-actuated distributor valve. Specifically, the motor assembly includes a housing having a substantially semicylindrical casing. An oscillatable vane piston is disposed within the cylinder casing for movement in either direction under the urge of fluid pressure. Thehousing also encloses a valve assembly comprising a pilot valve, a distributor valve, and a manually operable control valve.

The pilot valve is operatively associated with the vane piston through a cam arrangement whereby the pilot valve is mechanically actuated by the vane piston adjacent each end of its stroke. The pilot valve controls fluid connections to the servo actuated distributor valve, which controls the direction of piston movement. Fluid pressure application to the motor assembly is controlled by a manually operable valve including means for throttling the drain of fluid therefrom so as to control the speed of operation. The manual control valve also includes means for enabling movement of'the vane piston to a parked position, and concurrently therewith latches the servo distributor valve in position to prevent motor piston reversal. 4

In operation, the operator need only actuate a manual control rod so as to select the desired speed of operation. When the control rod is moved to the off position, the Wiper blades will automatically be moved to the parked position and remain at such a position under the urge of fluid pressure acting on one surface of thevane piston.

. Further objects and advantages ofthe present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown, and wherein similar numerals denote similar parts throughout the several views.

In the drawings: r

Fig. 1 is a view, partly in section and partly in elevation, of a fluid motor assembly of this invention.

Fig. 2 is an enlarged, fragmentary, sectional view of the latching means.

2 Figs. 3, 4 and 5 are schematic views illustrating motor operation and details of the valve assembly therefor.

With particular reference to Fig. l, the motor assembly is shown comprising a housing 10, which includes a semicylindrical cylinder casing 11 and a valve casing 12. A vane piston 13 having suitable sealing means 14 is attached to a rotatable shaft 15 within the cylinder casing 11, the vane piston being capable of oscillatory movement in both directions under the urge of fluid pressure.

Referring more particularly to Figures 3, '4 and 5, it may be seen that the vane piston 13 engages cams 16 and 17 at opposite ends of its stroke. Cam 16 is mounted for reciprocable movement within the valve housing 12 ina vertical direction, as viewed in Figs. 3 through 5. The cam member 16 includes an inclined surface 98, which is engageable with the conical end surface of a pilot valve plunger 30. In a like manner, the cam member 17 is disposed for reciprocable movement within the valve housing 12 and includes an inclined surface 99 engageable with the other conical end surface of the pilot valve plunger 30. The valve housing 12 has formed therein a pair of pressure passages 40 and 41, which communicate with the cylinder 11 on opposite sides of the vane piston 13. The valve housing 11 also includes a pair of drain passages 42 and 43, which, likewise, communicafe with the cylinder 11 on opposite sides of the piston 13. The pressure and drain passages 40, 41, 42 and 43 communicate with a bore within which a distributor valve plunger 51 is disposed for reciprocable movement.

The distributor valve plunger 51 includes three spaced lands 52, 53 and 54, which are separated by annular channels. Servo chambers 55 and 56 are formed by the bore 50,.which servo chambers communicate with the end surfaces of lands 52 and 54. Servo chamber 55 is connected by a passage 57 to ports 31 and 33 of the pilot valve bore 32. Servo chamber 56 is connected by a passage 58 to a pair of ports 34 and 36 of the pilot valve bore 32. The pilot valve, likewise, includes three lands separated by annular channels, and is capable of reciprocable movement in the horizontal direction, as viewed in Figures 3, 4 and 5, as controlled by the cams 16 and 1 The valve housing 12 includes a pressure supply passage 18 and a drain passage '19. The pressure supply passage 18- communicates directly with the distributor valve bore 50 between lands 52 and 53, as viewed in Fig. 3, and by a passage 20 with the annular channel between lands 53 and 54, as viewed in Fig. 4. The drain passage 19 communicates with a bore 21 having disposed therein for reciprocal movement, a manually operable control valve plunger 60. The bore 21 communicates with the distributor valve bore 50 through a pair of ports 22 and 23.

With particular reference to Figure 2, it may be seen that the control valve plunger 60 is formed with a tapered end portion 61, which constitutes a throttling means for the drain passage 19. The end of the plunger 60 also carries a pivotally mounted pawl 62 urged in a clockwise direction, as viewed in Fig. 2, by means of a coil compression spring 63, which spring is situated in a recess of the plunger 60. The pawl 62 includes a cam surface 64, such that when the plunger 60 is moved to the right, as viewed in Fig. 2, the pawl will be moved in a counterclockwise direction so as to permit movement of the plunger 60. However, when the plunger 60 is moved to l the ofl position of Fig. 2, the end thereof will project through the port, as shown in Fig. 2, and engage the end surface of land 53 of the distributor valve plunger 51, for a purpose to be more fully described hereinafter.

As is shown in Figures 3 through 5, the plunger 60 is also formed with a longitudinally extending slot 65 with in which the end of a pivotally mounted latch is received. The latch 70 is normally maintained in the substantially vertical position, as shown in Figures 3 and 4,

against a stop pin 71 of the cam 17. When the latch 70 is in this position, it may be seen that downward vertical movement of the cam 17 is limited by engagement of the stop pin 72 thereof with the end of latch 70. However, when the control valve plunger 60 is moved to the left, as shown in Figure 5, the latch 70 may be moved in a clockwise direction out of the path of stop pin 72, so that upon movement of the vane piston 13 in a clockwise direction with the shaft 15, the cam member 17 may be further depressed, for a purpose which willappear more fully hereinafter. The latch 70 is normally maintained against the stop pin 71 of the cam 17 by-means of a leaf spring 73.

Operation The motor operates as follows. With the control valve plunger 60 in the position of Figure 3, pressure fluid will be applied through passage 17 to passage and chamber 22 of the cylinder 11. At this time, chamber 24 of the cylinder 11 will be connected to drain through passage 43 and passage 19. Accordingly, the vane piston 13 will swing in a clockwise direction to the position of Figure 4, and thereby depress cam 17, which will cause movement of the pilot valve plunger 3% to the right from the position of Figure 3 to the position of Figure 4. In this manner, the pilot valve will apply pressure fluid through port 36 to passage 58 and servo chamber 5'6 of the distributor valve, from port 25, which communicates with. passage 26 and the passage 20. At this time, servo chamber will be connected to drain through passage 57, port 33, port 27 and passage 28 to the bore 21 and the passage 19. Accordingly, the distributor valve plunger 51 will be moved to the right from the position of Figure 3 to the position of Figure 4, whereupon pressure fluid from passage 19 will be applied through passage 2i and passage 41 to chamber 24 of the cylinder 11. Simultaneously, therewith chamber 22 of the cylinder 11 will be connected to drain through passage 42, port 22, bores 21 and passage 19.

The vane 13 will now move in a counterclockwise direction until the vane piston engages cam 16 whereupon the pilot valve 36 will be moved from the position of Fig. 4 to the position of Fig. 3. In this manner, the pressure and drain connections to the servo chambers 55 and 56 of the servo distributor valve plunger 51 Will'be reversed and the vane piston 13 will be sustained in oscillation. In order to actuate oscillatable wiper blades, not shown, it is only necessary to connect the transmission means therefor to the oscillatable shaft 15.

In order to control the speed of oscillation of vane piston 13, the operator need only actuate the control rod, or Bowden wire, 75 of Figure 1, which positions the control valve plunger 60 so that the end 61 thereof throttles the drain flow through passage 19. In Figure 3, the plunger 60 is disposed for full speed operation, While in Figure 4 it is disposed for one-half speed operation.

Whenpthe plunger 60 is moved to the position of Fig:

ure 5, the vane piston 13 will be moved to the parked position and retained at such position by fluid under pressure. As is seen in Figure 5, the pawl 62 carried-bythe' plunger 66 is situated in the port 23, and engages the end of land 53 so as to prevent movement of the plunger 51 to the right, as viewed in Fig. 5. When the plunger 60 is moved to the position of Fig. 5, the latch 70'is moved in a clockwise direction by compressingleaf spring" 73 so that stop pin 72 no longer engages the end thereof;

Accordingly, the vane piston may further depress the cam 17 under the urge of-fluid pressure in chamber 22-, thereby increasing the amplitude of oscillation'imparted to the shaft 15, so as to move the wiper blades, not

shown, to the parked position. The vane piston 13 will be retained in this position by means offluidunder pres:

sure applied to chamber 22' of. the cylinder 11 throughpassages. 4tl'and 18, while chamber 74 is-connected= to drain through passages 43'and 19.

In order to resume wiper operation, it is only necessary to move the controlvalve plunger to the right, as viewed in Fig. 5, to the position of either Figs. 3 or 4 whereupon the valve plunger 51 will be freed for movement, and the latch 70 will be moved in a counterclockwise direction so as to limit downward movement of the cam 17.

From the foregoing, it is manifest that the present invention provides a fluid motor particularly adapted to operate oscillatable windshield wiper blades. Moreover, the present invention provides fluid pressure means for maintaining the blades in the parked position when the wiper motor is not in operation. Furthermore, the instant fluid motor employs valve means controlled by oscillation of the. piston for sustaining piston movement.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A fiuid pressure motor including in combination, a cylinder, an oscillatable vane piston disposed in said cylinder capable of fluid pressure actuation in either direction, a pair of reciprocable cams disposed in said cylinder engageable by said piston adjacent the ends of its stroke, a reciprocable pilot valve plunger operatively associated with said cams and movable thereby, and a servo actuated distributor valve having ports and passages connected with said cylinder on opposite sides of said piston, said pilot valve controlling the application of pressure fluid to opposite ends of said distributor valve so as to position the same whereby said vane piston may be sustained in oscillation.

2. A- fluid pressure motor including in combination, a cylinder, an oscillatable vane piston disposed in said cylinder and dividing the same into two chambers, said piston being capable of fluid pressure actuation in either direction, cam means'disposed in each cylinder chamber and engageable by said piston so as to be reciprocated thereby, valve means controlled by said cam means for alternately directing pressure fluid to opposite chambers of said cylinder so as to sustain said piston in oscillation, and means associated with one of said cam means- 7 for effecting movement of said piston beyond its normal working stroke-and retaining the same in said position.

3. A fluid pressure motor including in combination, a cylinder, an'oscillatable piston disposed in saidcylinder capable offluid pressure'actuationin either direction, said piston dividingsaid cylinder into two chambers, a cam memberdisposed in each cylinder chamber and engage-' able by said pistonso-as to be moved thereby, a pilot valve operatively associated with said cam'members and reciprocable'thereby, a servo actuated distributor valve operatively associated with said pilot valve and controlled thereby for directing pressure towopposite chambers of said motor so as to sustain said piston in oscillation, and means for latching said distributor valve in position so as to prevent movement of said piston.

4. A fluid pressure motor including in combination, a cylinder, a piston disposed in said cylinder anddividing the same into two chambers, said piston being capable of fluid pressure actuation in either direction, a cam member disposed in each cylinder chamber and engageable by said piston so as to be moved thereby, a pilot valve operatively associated with 'saidcam members so as to'be reciprocated thereby, a'servo' actuated distributor valve fo'r controlling the application of pressure fluid to opposite chambers of said motor, said distributor valve being controlled by said pilotvalve, and'a manual control valve for controlling the speed of motor operation.

5. A fluid pressure motor including in combination, a cylinder, an oscillatable piston disposed in said cylinder and dividing the same into two chambers, said piston being capable of fluid pressure actuation in either direction, a reciprocable cam member disposed in each cylinder chamber and engageable by saidpiston so as to be rep cated thereby, a pilot valve oper'atively associated with said cam members so as to be reciprocated thereby, a servo actuated distributor valve for controlling the application of pressure fluid to opposite chambers of said cylinder, the position of said distributor valve being controlled by said pilot valve, and a manual control valve for controlling the operation of said motor including means operatively associated with one of said cam members so as to permit extended movement thereof and simultaneously therewith latch the servo actuated distributor valve in position whereby the vane piston may be moved beyond its working stroke and to a parked position.

6. A fluid pressure motor including in combination, a cylinder, a movable member disposed in said cylinder capable of fluid pressure actuation in either direction and dividing said cylinder into two chambers, a movable cam disposed in each cylinder chamber and engageable by said movable member so as to be moved thereby adjacent the ends of its stroke, a reciprocable pilot valve plunger operatively associated with said cams and movable thereby, and servo actuated valve means having ports and passages connected with said cylinder chambers, said pilot valve controlling the application of pressure fluid to opposite sides of said servo actuated valve means so as to position the same so as to eflect continuous movement of said movable member.

7. A fluid pressure motor including in combination, a cylinder, a movable member disposed in said cylinder capable of fluid pressure actuation in either direction and dividing said cylinder into two chambers, cam means disposed in each cylinder chamber and engageable by said movable member so as to be moved thereby, valve means controlled by said cam means for alternately directing pressure fluid to opposite chambers of said cylinder so as to maintain said member in a state of continuous movement, a latch engageable with one of said cam means for limiting movement thereof by said piston, and manually operable means for removing said latch so as to permit extended movement of said one cam means by said movable member so as to permit movement of said member beyond its normal working stroke.

8. A fluid pressure motor including in combination, a cylinder, a movable member disposed in said cylinder capable of fluid pressure actuation in either direction and dividing said cylinder into two chambers, a reciprocable cam disposed in each cylinder chamber and engageable by said movable member so as to be reciprocated thereby, valve means controlled by said cams for alternately directing pressure fluid to opposite chambers of said cylinder so as to maintain said member in a state of continuous movement, one of said cams having a stop pin thereon, a pivotally supported latch engageable with said stop pin for limiting movement of said one cam by said movable member, and manually operable means for effecting pivotal movement of said latch out of engagement with said stop pin to permit extended movement of said one cam by said movable member whereby said movable member may be moved beyond its normal working stroke.

9. A fluid pressure motor including in combination, a

cylinder, a movable member disposed in said cylinder capable of fluid pressure actuation in either direction and dividing said cylinder into two chambers, valve means controlled by said movable member adjacent each stroke end thereof including a distributor valve for alternately directing pressure fluid to opposite chambers of said cylinder so as to maintain said member in a state of continuous movement, a manual control valve for controlling the speed of motor operation, and a spring biased pawl pivotally supported on said manual control valve and automatically engageable with said distributor valve for latching the said distributor valve in position when said manual control valve is moved to the olf position.

10. A fluid pressure motor including in combination, a cylinder, a movable member disposed in said cylinder capable of fluid pressure actuation in either direction and dividing said cylinder into two chambers, a servo actuated distributor valve for controlling the application of pressure fluid to opposite chambers of said cylinder, means actuated by said movable member adjacent each stroke end thereof for controlling the actuation of said distributor valve, a manual control valve for controlling motor operation, and a spring biased pivotally supported pawl mounted on said manual control valve and engageable with said distributor valve for latching the said distributor valve in position thereby preventing movement of said movable member when the manual control valve is moved to the OE position.

11. A fluid pressure motor including in combination, a cylinder, a movable member disposed in said cylinder capable of fluid pressure actuation in either direction throughout a running stroke, pilot valve means actuated by said movable member adjacent the ends of the running stroke, a fluid pressure actuated distributor valve controlled by said pilot valve means for alternately directing pressure fluid to opposite sides of said member, and mechanical means engageable with said distributor valve for preventing fluid pressure actuation thereof adjacent one end of the running stroke to permit movement of said member beyond said one end of the running stroke to a parked position.

References Cited in the file of this patent UNITED STATES PATENTS 637,881 Marsh Nov. 28, 1899 994,231 Yost June 6, 1911 1,019,388 Weber et a1. Mar. 5, 1912 1,200,681 Woodward Oct. 10, 1916 1,534,238 Mercer Apr. 21, 1925 1,853,758 Brumm Apr. 12, 1932 1,880,727 Blood Oct. 4, 1932 2,057,317 Ruud Oct. 13, 1936 2,161,216 Wood June 6, 1937 2,263,003 Koppelman Nov. 18, 1941 2,385,084 Koppelman Sept. 18, 1945 2,450,733 Lane et a1. Oct. 5, 1948 2,627,251 Sprague et a1 Feb. 8, 1953 2,664,074 OShei Dec. 29, 1953 

